Ever increasing demand for more content displayed in a single display has led to an increase in production and sales of display walls. Display walls generally include multiple display monitors positioned next to one another in a tiled fashion to present a single large image. Using relatively large flat-panel display monitors and/or rear-projection monitors and tiling them in grid sizes of two-by-two, three-by-three, and three-by-four, among others, an integrated displayed image can occupy an entire wall of a room. Display walls are frequently used in large system command and control centers such as war rooms, utility management centers, and traffic monitoring centers.
Frequently, the content displayed in a display wall includes motion video from multiple sources such as highway-mounted traffic monitoring cameras. For flexibility in viewing these multiple video sources, it is desirable to see each one in a “window,” which can be made any size (regardless of the native resolution of the source) and can be positioned at any location within the display wall regardless of the boundaries of the individual constituent display devices. Windows are known and conventional elements of a graphical display and are not described further herein. The transfer of high data-rate digital video streams from multiple sources to the multiple displays of a tiled display wall represents a particularly difficult problem. Since the tiled display monitors represent an integrated display, there is generally a central controller for the various display monitors. The multiple video streams are typically routed through the central controller. The central controller typically includes a number of video capture devices which receive and encode video streams into digital data streams and a number of video controller devices to drive the individual pixels of the respective tiled display monitors of the display wall. Such central controllers typically experience debilitating data bottlenecks at the bus or buses through which the respective video data streams travel within the central controller.
The buses represent a bottleneck because the aggregate bandwidth required to handle all incoming signals and distribute those signals at high update rates to any combination of the display devices far exceeds the capacity of a single bus. A bus-oriented architecture may suffice in a small system with five to ten input and output devices, but bus-oriented architectures cannot be effectively scaled up to handle larger systems. In other words, doubling the number of video sources and destinations requires much more than a doubling of the number of buses to handle the requisite data transfer bandwidth increase resulting from such a doubling. Multiple buses can be used, each bus connecting a subset of input devices to a subset of output devices, but this leads to a loss in flexibility as to where each incoming video signal can be displayed. Specifically, a video stream from a particular input device would be displayable only on a selected few of the output display devices. Thus, the end user could not have free reign in determining where a particular video stream is to be displayed in a display wall.
What is needed is a more efficient interconnection mechanism between the capture devices and the display devices.